Having the latestest 20,000,000 lumins bike lights is great but they come at a price.
There are a fair few powerful bike lights available on eBay from China that are very bright, though not so good on a long ride of more than a hour.
I'm not sure I would take a chance on some of these lights from China as some have been reported to bursting into flames while on charge or while being used on the bike.!!

I think I'd prefer to pay for a genuine branded make and have the peace of mind and a warenty I can trust.

"There is no glory in Practice.. But without Practice there is no glory"